wide, worthless
曠 centers on vast, open emptiness: something wide and spacious, or by extension, hollow and worthless.
曠 combines 日 (sun) with 廣 (broad, spacious), suggesting sunlight filling a wide, open space. The worthless sense likely extends from the idea of emptiness.
The sun 日 spreads across a broad, open area 廣, making everything wide and empty. When a space is too empty, it feels worthless.
For コウ, imagine a wide, empty field under the sun, and a single crow (コウ) cawing in the vastness: crow -> コウ.